1. Technical Field
The invention relates to a helical compression spring which, as a component of a two-part oil scraper ring in a piston of an internal combustion engine, is provided for pressing the second component of such an oil scraper ring, namely the so-called base body that is in sliding contact with a cylinder or a cylinder liner, against the cylinder wall. The present invention relates further to a method for coating such a helical compression spring.
2. Related Art
As mentioned, in the described two-part oil scraper ring, the helical compression spring is located on the inside of the arrangement, in other words between the base body of the piston ring, which is in sliding contact with the cylinder wall, and the bottom of the piston ring groove. Relative movements occur between the base body and the helical compression spring due to dynamic stress during operation of the engine. This movement can lead to so-called secondary wear, which can manifest itself in the base body in the form of channels in the groove and on the spring in the form of abraded material. The spring can catch in the channels in the groove, which impairs the scraping action of the oil ring. Furthermore, there can be a reduction in the tangential force required to perform the function.